JPH0274615A - Carbon fiber-based porous hollow fiber membrane and production thereof - Google Patents

Abstract

PURPOSE:To obtain the subject hollow fiber membrane having excellent heat-resistance by mixing an acrylonitrile(AN) polymer, a thermally decomposable polymer and a solvent, spinning and drawing the mixture and subjecting the obtained AN hollow fiber to flame-resistant treatment and carbonization treatment to make a porous membrane. CONSTITUTION:An AN hollow fiber is produced by mixing (A) an AN polymer containing 90-100mol% of AN unit with (B) a thermally decomposable polymer decomposed at <=600 deg.C to form a low-molecular weight compound (preferably polystyrene, etc.) and (C) a solvent (preferably DMF, etc.) and spinning and drawing the mixture. The obtained hollow fiber is subjected to flame-resistant treatment and then carbonized at >=400 deg.C to make a porous membrane. The objective hollow fiber membrane produced by the above process contains small pores continuously connected from the inner wall surface to the outer wall surface of the hollow fiber membrane, has a peak of the pore radius at 10-1,000nm (determined by a differential curve of pore volume) and a total pore volume of 0.1-1cm<3>/g, is bendable with a radius of curvature of <=10cm and exhibits a decomposition temperature of >=300 deg.C corresponding to the temperature to decompose 10wt.% of the hollow fiber membrane measured by TGA.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a novel carbon fiber-based porous hollow fiber membrane with excellent heat resistance and a method for producing the same.

[Conventional technology]

Several types of activated carbon fibers for adsorption separation are already known. Examples include those made from regenerated cellulose fibers, acrylonitrile fibers, phenol fibers, and pitch fibers. Fibrous activated carbon has many advantages over granular activated carbon, such as a significantly larger contact area and faster adsorption and desorption rates. Furthermore, by using hollow fibers, it is freed from complicated processes such as adsorption and desorption, and by simply passing the fluid through the inside of the hollow fibers under pressure, it is possible to separate the fluid from the fluid, making an energy-saving process possible.

On the other hand, regarding hollow activated carbon fiber, Japanese Patent Application Laid-Open No. 48-8
Publication No. 7121 has a hollow ratio of 10 to 80% and a specific surface area of 40%.
A hollow fiber is disclosed in which voids are formed in a carbon material of 0 m27 g or more and has the function of adsorbing trace substances in gas or liquid. The manufacturing method for this hollow fiber is to crosslink the skin part of a fiber made from phenol, elute the uncrosslinked core part with a solvent, carbonize the obtained hollow fiber, and then activate it with an oxidizing gas such as water vapor. This method makes the material porous. Therefore, the pore radius is micropores of 10 to 20×, and the hollow portions of the hollow fibers obtained lack uniformity, have high fluid resistance, and have a low permeation rate.

JP-A-58-91826 discloses a pitch-based hollow carbon fiber, but the hollow inner diameter is as small as 10 μm or less, and there are no pores in the membrane wall (it is not intended as a separation membrane.

Also, JP-A-60-179102 and JP-A-60
Publication No. 202703 discloses a carbon membrane with a multilayer structure, but the former carbon membrane has at least one microporous dense layer, and at least one layer has large pores to accelerate the permeation rate. Moreover, the orientation coefficient of the multilayer structure as a whole is as small as 0.7. Furthermore, the latter carbon membrane also has an extremely fragile membrane structure, consisting of a porous layer with separation ability and a sponge-structured porous layer with voids with a maximum pore diameter of 5 μm or more to accelerate the permeation rate. It is impractical.

Furthermore, Japanese Patent Application Laid-open No. 61-47827 discloses carbonized hollow fibers made from polyvinyl alcohol fibers, in which a dehydrating agent is infiltrated only into the surface layer, and the dehydrating agent is infusible in the carbonization process. The remaining central portion is melted and removed to make it hollow, and the porous hollow carbon fiber is produced by activation treatment with steam.

Furthermore, JP-A No. 63-4812 proposes a method for producing a carbon membrane with pores, in which a hollow fiber membrane in which pores have been previously formed by an extraction method is treated with an aqueous hydrazine solution, and then flame-resistant and carbonized. ing.

However, these porous hollow carbon fibers from the prior art have many micropores with a size of 1 to 5 nm (and from a practical standpoint, they lack physical properties such as strength).

The average radius of the pores of activated carbon fibers and porous hollow carbon fibers according to the prior art are both as small as 1 to 5 nm.
Although it is suitable for the adsorption and separation of substances with a relatively small molecular weight from the gas phase, it is not suitable for the adsorption and separation of substances with a relatively large molecular weight from the gas and liquid phases as intended by the present invention. Furthermore, most of the fibers produced by these prior art techniques have low elongation and lack flexibility.

[Problem to be solved by the invention]

In view of this current situation, the present invention has a pore radius of 10 to 1100.
The object of the present invention is to provide a carbon fiber-based porous hollow fiber membrane having a pore distribution with a sharp peak in a range called 0n macropores, and an efficient method for producing the same.

[Means to solve the problem]

The present invention has pores that are continuously connected from the inner wall surface to the outer wall surface of the hollow fiber membrane, and the maximum value of the pore radius determined from the pore volume differential curve exists in the range of 10 to 1000 nm, and the total pore diameter is 10 to 1000 nm. The pore volume is 0.1 to 1 crn3/I, the radius of curvature when bent is 10 cm or less, and the temperature at which 10% by weight of the hollow fiber membrane decomposes as measured by TGA is at least about 300°.
It is a carbon fiber porous hollow fiber membrane with excellent heat resistance.

In the carbon fiber porous hollow fiber membrane of the present invention, it is preferable that the tensile elongation of the single fibers is at least 0.8%.

The maximum value of the pore radius determined from the pore volume differential curve in the present invention refers to the maximum value of the pore radius distribution curve of cylindrical equivalent pores measured by mercury intrusion method. Further, the total pore volume indicates the cumulative value of pore volumes.

The most important feature of the carbon fiber porous hollow fiber membrane of the present invention is that it has pores that communicate from the inner wall surface to the outer wall surface of the hollow fiber membrane, and the pore radius determined from the pore volume differential curve. Since the maximum value of is 10 to 1D00 nm, it has a large pore radius compared to conventional activated carbon fibers, and it is difficult to absorb substances from the gas phase or liquid phase that contain substances with relatively large molecular weights. Suitable for adsorption and separation of substances.

In addition, it has excellent flexibility, especially since the radius of curvature when bent is 10 crn or less. If the carbon fiber-based porous hollow fiber membrane does not satisfy any one of the various physical properties described above, it is not preferable because it will not be able to exhibit the effects as a porous hollow fiber membrane that is the object of the present invention.

As a preferable method for producing the carbon fiber porous hollow fiber membrane of the present invention, for example, the acrylonitrile unit is 90 to 1
00 mol% acrylonitrile polymer (A) and 6
The acrylonitrile-based hollow fiber obtained by mixing the pyrolyzable polymer (B), which is thermally decomposed to lower the molecular weight at a temperature of 00°C or less and the solvent (C), and then spinning and drawing, is subjected to flame-retardant treatment. An example of this method is to perform a carbonization treatment at a temperature of 400° C. or higher to make the material porous.

When producing a carbon fiber porous hollow fiber membrane, the solubility parameter δ of the acrylonitrile polymer (N is generally around 15.4, and that of the thermally decomposable polymer (B) is 9 to 12.2. Most of them are within this range, and they are often poorly compatible with each other. Therefore, depending on the combination of the acrylonitrile polymer prisoner and the thermally decomposable polymer (B), a compatibilizer (
By mixing D), mutual compatibility can be improved.

The acrylonitrile polymer (A) used in the practice of the present invention includes 90 to 100 mol% of acrylonitrile units and 0 to 10% of monomers copolymerizable with acrylonitrile.
It is an acrylonitrile homopolymer or copolymer composed of mol%. Specific examples of copolymerizable monomers include acrylic acid, methacrylic acid, itaconic acid and derivatives thereof, such as methyl acrylate, ethyl acrylate, benzyl acrylate, methyl methacrylate, ethyl methacrylate, and acrylamide, methacrylamide, etc. Examples include amide derivatives, halogenated monomers such as vinyl acetate, vinyl chloride, and vinylidene chloride, and sulfonic acid derivatives such as sodium methacrylsulfonate and sodium styrene sulfonate, but are not necessarily limited to these.

As the acrylonitrile polymer (A), polyacrylonitrile, acrylonitrile-methacrylic acid copolymer,
Particularly preferred are acrylonitrile-methyl acrylate-itaconic acid copolymer, acrylonitrile-methyl acrylate-methacrylic acid copolymer, and the like. The degree of polymerization indicated by the specific viscosity of the acrylonitrile polymer (b) is preferably from 0.1 to 0.4, particularly from 0.2 to 0.3. If it is outside this range, it is not preferable because the spinning operation becomes difficult and the performance of the fiber obtained by spinning tends to be poor.

The thermally decomposable polymer (B) is one that is thermally decomposed at a temperature of 600° C. or lower to reduce its molecular weight, and is soluble in the solvent of the acrylonitrile polymer. Specific examples of such thermally decomposable polymers include aromatic vinyl monomers such as styrene, α-methylstyrene, and vinyltoluene, and aliphatic vinyl monomers such as vinyl chloride, vinyl alcohol, and vinyl acetate. , a homopolymer of methacrylate monomers such as methyl methacrylate, ethyl methacrylate, n-methyl methacrylate, or 51 mol% or more of these monomer units, and other copolymerizable monomer units other than acrylonitrile 49 Examples include copolymers composed of mol% or less. Particularly preferred are styrene polymers, vinyl chloride polymers, and methyl methacrylate polymers.

Specific examples of other copolymerizable monomers include acrylate monomers such as methyl acrylate, ethyl acrylate, and n-phthyl acrylate, as well as acrylic acid and methacrylic acid.

The degree of polymerization indicated by the specific viscosity of the thermally decomposable polymer (B) is determined by adjusting the ratio of the acrylonitrile polymer (A) to facilitate adjustment of the viscosity when preparing a mixed dispersion with the acrylonitrile polymer (Al). It is preferable that the specific viscosity determined by the same method as the viscosity measuring method is in the range of 0.1 to 0.4, particularly 0.2 to 0.6.

The solvent (C) can be a common solvent for the acrylonitrile polymer (N) and the thermally decomposable polymer (B) and the compatibilizer (D).
) is preferably dimethylacetamide, dimethylformamide, dimethylsulfoxide, or the like.

Compatibility agent (D) is acrylonitrile) IJ-based polymer (A)
and thermally decomposable polymer CB), which can act as a compatibilizer that exhibits a compatibility effect with both. There are a variety of substances that exhibit a compatibility effect, from low molecular weight ones such as oligomers to high molecular weight ones, but specifically, those that are compatible with the acrylonitrile polymer (A), or those that are made from the same monomer. Segment composed of (a) and segment) (b) that is similarly compatible with the thermally decomposable polymer (B) or composed of the same monomer, in the same polymer chain. For example, a block copolymer or a graft copolymer is preferably used. Such a block copolymer or graft copolymer can be produced by a known method, for example, by the method described in Japanese Patent Publication No. 61-39978 as an example of producing a block copolymer or graft copolymer.

The compatibilizer (D) is used to mix the acrylonitrile polymer (A) and the thermally decomposable polymer (B) together with the solvent (C).
) It has the effect of making the solution into uniform small dispersed particles and making the resulting dispersion solution stable. Furthermore, this compatibilizer (D) not only improves the compatibility effect, but also controls the size of the dispersed phase of the thermally decomposable polymer (B), which becomes the island component, which ultimately improves the compatibility effect. This leads to controlling the size of the fibrils of the thermally decomposable polymer (B), which is the basis of the pore diameter of the carbon fiber porous hollow fiber membrane. Therefore, the amount of compatibilizer (DJ) used depends on the final amount obtained.It is also related to the size of the pore radius of the porous hollow fiber membrane. The size distribution of the pores becomes small (and the pore radius tends to be uniformly distributed).

The compatibilizer (D) includes 60 mol% or more of acrylonitrile, 10 mol% or more of monomers that are constituent components of the thermally decomposable polymer (B), and 10 mol% or less of other monomers copolymerizable with these. A block copolymer or a graft copolymer composed of these materials is preferred.

When producing a carbon fiber porous hollow fiber membrane, the preferred mixing ratio of the acrylonitrile polymer (A), the thermally decomposable polymer (B), and the compatibilizer (DJ) is 10 to 90% of the acrylonitrile polymer (A). Weight% preferably 20-8
0% by weight, 10 to 90% by weight of the thermally decomposable polymer (B), preferably 20 to 80% by weight, and 0 to 1% of the compatibilizer (D)
0% by weight, preferably 0 to 5% by weight [with the exception of component A),
The total amount of component (B) and component (D) is 100% by weight]
It is.

If the amount of the thermally decomposable polymer (B) mixed is less than 10% by weight, it is not preferable because it is difficult to obtain pores communicating from the inner wall surface to the outer wall surface of the porous hollow fiber membrane finally obtained. Furthermore, as the amount of the thermally decomposable polymer (B) mixed increases, the number of communicating pores increases and the pore volume also increases.
If it exceeds % by weight, the total pore volume increases, resulting in a decrease in the strength of the finally obtained porous hollow fiber membrane, which is not preferable.

As the mixing amount of the compatibilizer (D) increases, the size of the dispersed particles decreases, and as a result, the stability of the dispersion solution increases. This contributes to reducing the radius of the pores and the distribution of pore sizes in the porous hollow fiber membrane that is finally obtained, but if the mixing amount exceeds 5% by weight, Since the effect of addition is saturated, a mixing amount of up to 5% by weight is sufficient.

The polymer concentration in the mixed solution of mixed polymer and solvent (C) is 10 to 65% by weight, preferably 15 to 30% by weight. Mixing may be performed simultaneously during dissolution. Alternatively, each may be dissolved individually, and the solutions may be mixed together immediately before spinning using a known static kneading element that does not require a driving part. In this case, a compatibilizer (DJ is not necessarily required). The effect of mixing is controlled by the number of elements. In other words, as the number of elements increases, the radius of the pores of the porous hollow fiber membrane finally obtained becomes smaller. .

If the concentration of the polymer in the mixed solution is less than 10% by weight, the strength characteristics of the finally obtained porous hollow fiber membrane will deteriorate, which is not preferable. Moreover, if it exceeds 35% by weight, the viscosity of the mixed solution becomes high, which causes problems such as lack of stability of the mixed solution and difficulty in filtration, which is not preferable.

The mixed dispersion solution is spun into a hollow shape using, for example, an annular slit or a saltpeter-type nozzle. The spinning method can be any of wet spinning, wet-dry spinning, and dry spinning, and wet-dry spinning is particularly preferred.

To explain the case of spinning using a dry-wet spinning method, for example, a solution discharged from a saltpeter type nozzle once travels in the air, and then is introduced into a coagulation bath and coagulated. It is preferable to use a coagulant that has a relatively gentle coagulating force because phase separation proceeds gently and a strong film is easily obtained. Usually, an aqueous solution of a solvent is used, and the solvent concentration is preferably 40 to 85% by weight, particularly 60 to 80% by weight, and solidification is preferably carried out at a temperature of 40°C or lower, particularly 20°C or lower. If it is outside this range, it is not preferable because the hollow fiber membrane tends to be fragile.

It is then washed in warm or hot water and stretched. Stretching is performed in two or more stages, and the total stretching ratio is 3 times or more, preferably 5 times.
Stretched more than twice as long. It is preferable that the stretching is as high as possible without causing destruction of the fiber structure, but the upper limit of the total stretching ratio varies depending on the stretching method and the stretching medium, but a guideline is approximately 80% of the stretching ratio at which stretch breakage occurs. Next, the obtained drawn fiber is dried to produce a hollow fiber membrane blend mainly of an acrylonitrile polymer (I) and a thermally decomposable polymer (B).

The size of the hollow fiber membrane can be changed depending on the nozzle, solution discharge amount, stretching conditions, etc., but the inner diameter is approximately 20 to 100 mm.
It is easy to manufacture a film thickness of 0 μm in a range of 174 to 1/10 of the inner diameter. Then, the obtained polymer blend hollow fiber membrane is heated with an oxidizing gas (02,
gas containing o8, S, No, So□, etc.) in the atmosphere,
It is usually treated in air to make it flame resistant. When flame-retardant treatment is performed, the hollow fiber membrane fibers are controlled so as not to shrink in the length direction. Excessive shrinkage in the flameproofing process is undesirable because it reduces the mechanical strength of the hollow fiber membrane fibers. Excessive stretching is also undesirable as it may cause the hollow fiber membrane fibers to break. Therefore, the elongation during the flameproofing process is 0 to 15
It is preferable to carry out the flame-retardant treatment by controlling the amount within a range of 1.

Next, the obtained hollow fiber membrane subjected to flame-retardant treatment was heated to 400~
1200°C1 Preferably in an inert gas (N2, Ar, He, etc.) atmosphere at a temperature of 600 to 1200°C or in a mixed gas of an inert gas and an oxidizing gas (HCI, N20, CO10□, etc.) is carbonized in an inert gas, usually nitrogen gas, while controlling the tension. In this process, the fifuryl components of the thermally decomposable polymer (B), which are arranged along the fiber axis, are thermally decomposed and depolymerized, decomposed into low molecules such as monomers, and released. It can be a hollow fiber membrane.

Unlike a sponge structure, the porous structure of the carbon fiber-based porous hollow fiber membrane of the present invention is composed of countless pores parallel to the fiber axis, and these pores extend from the inner wall surface to the outer wall surface of the hollow fiber membrane. These are pores that are connected continuously. This can be observed by small-angle X-ray scattering intensity or by a scanning electron microscope. It is thought that such a unique porous structure is formed for the following reasons.

That is, during spinning from a mixed solution, each dispersed particle is subjected to the action of shear stress and stretching, and is arranged parallel to the fiber axis, and the fibrils of each polymer phase separate from each other.
Intertwined to form a network structure. Therefore, due to the heat generated during carbonization, the fibrils arranged parallel to the fiber axis of the polymer (BJ) thermally decompose and escape, forming countless pores, and as a result, such a porous structure is finally obtained. This makes the porous hollow fiber membrane superior in strength and flexibility properties.The carbonaceous structure of the acrylonitrile polymer (which has a fibrillar structure) is also a structure in which thin fibrils are connected parallel to the fiber axis; The hollow fiber membrane of the present invention is made strong.Furthermore, since it is carbonaceous, it also has excellent heat resistance.

The carbon fiber porous hollow fiber membrane of the present invention is characterized by a very sharp pore size distribution of pore radii determined from a pore volume differential curve, so it exhibits high separation performance and has a large total pore volume per unit. The number of pores per membrane thickness is large, making the water permeation rate high. The carbon film of the present invention also has high chemical stability (and exhibits strong resistance to all I)H regions and most chemical solutions.

The carbon fiber porous hollow fiber membrane of the present invention can provide a module that can be used at a higher temperature in the range of 600°C to 650°C at which the weight loss in air reaches 10%. Because of these excellent properties, it is used for various purposes, such as the separation and purification of pyrogenes and polymer substances in the pharmaceutical industry, gas separation in the chemical industry, especially the separation of organic gases and the purification of organic chemicals.
It can be effectively used for clarifying alcoholic beverages, soft drinks, soy sauce, vinegar, etc. in the food industry. Furthermore, it is particularly useful in fields that require purification of products from enzymes and separation of proteins and enzymes in the pioneering industry, separation of proteins, viruses, bacteria, etc. in the medical field, and fields that require sterilization and sterilization at high temperatures. It is. It can also be used in fields that require heat resistance, such as filtration membranes for condensate turbine heater drains in power plants.

〔Example〕

Hereinafter, the present invention will be specifically explained with reference to Examples. Note that "parts" in the following description indicate parts by weight.

1) The specific viscosity of the polymer was measured at 25°C by dissolving 0.1y of the polymer in 100ml of dimethylformamide containing 0.1N Rodan Noda.

2) The pore distribution structure of the carbon fiber porous hollow fiber membrane is CAR
It was measured using Porosimeter 200 manufactured by LOERBA, and the pore radius was determined as a cylindrical equivalent radius.

3) Specific surface area is measured by methanol isothermal adsorption curve, BET
Calculated by applying the formula.

4) Single fiber strength and elongation were measured using Tensilon UTM-II type (manufactured by Toyo Sideki Co., Ltd.) at a tensile rate of 100%/min.

5) The radius of curvature at the time of bending is the minimum radius of curvature when no bending or cutting occurs when the porous hollow fiber membrane is wound around a cylinder with a radius of 1800 or more, and is used as a guideline for flexibility. did.

6) Heat resistance was determined by dynamic thermograpimetric analysis (TGA) of the sample.
It is shown as the temperature at which 10% by weight of the sample decomposes when measured in an air atmosphere at a heating rate of 10° C./min.

7) Water permeation rate is effective length 10 crn, effective surface area 1
Pressure 1kg/crn2 from one side of ml prototype module
The amount of water permeated from the inner wall of the hollow fiber to the outer wall was measured.

Example 1 Acrylonitrile (hereinafter abbreviated as AN) 98 mol%,
AN/MAA copolymer (A) with a specific viscosity of 0.24 composed of 2 mol% of methacrylic acid (hereinafter abbreviated as MAA)
60 parts and methyl methacrylate (hereinafter abbreviated as -) 9
9 mol%, methyl acrylate (hereinafter abbreviated as MA) 1
MMA with specific viscosity 0.21 composed of mol%/M
40 parts of a thermally decomposable copolymer (B) which is a copolymer A;
The mixing amount of the compatibilizer (D,) prepared by the following method is 0 to 0.
Four types of mixed solutions shown in Table 1 were prepared by changing 5 parts.

Note that the solvent (C) is dimethylformamide (hereinafter referred to as DMF).
), the polymer concentration was set to 26% by weight, and the mixed solution was kept at a temperature of 60° C. to defoam.

Preparation of compatibilizer (Dl) Dissolve 1 part of dichlorohexano/peroxide (Veroxa I (manufactured by NOF Corporation) in 100 parts of Mabutsu, and add 800 parts of pure water.
and Pellex OTP as an emulsifier (manufactured by NOF Corporation)
After adding 1 part to the reaction vessel and sufficiently purging with an inert gas, the temperature was maintained at 40°C, and the pH was adjusted to 3 with 0.76 parts of Rongalit and an aqueous sulfuric acid solution, and then polymerization was started. Stirring was continued to complete the first stage emulsion polymerization in 150 minutes. Next, in the second stage, after adding 2 parts of Hough to this emulsion, the temperature was raised to 70°C and stirring was continued for 150 minutes again.
Furthermore, 4 parts of Glauber's salt was added and stirred for 30 minutes to complete the polymerization. The polymer was taken out, filtered, washed with water, and dried until the polymerization rate was 6.
A block copolymer compatibilizer (D,) with a specific viscosity of 0.19 and 5.7% was obtained.

Outline '1. Ommφ, inner diameter 1.5mmφ sheath and 1.0
For each type of mixed solution prepared from the sheath of the saltpetre nozzle, which consists of 8 parts of m-butt φ, 10 parts of air is mixed with 8 parts of the mixed solution.
After each was discharged with water injection pressure and run in the air for 5c7n, it was introduced into a coagulation bath containing a 70% by weight DMF solution at a temperature of 2°C, spun and coagulated, and then washed in warm water at 60°C. It was stretched 2.8 times. Then, it was stretched twice in hot water at 98°C. This fiber with a total stretching ratio of 5.6 times is
The fibers were dried through a hot roll at 60° C. to produce four types of polymer blend hollow fibers.

These four types of hollow fibers were each set in a stainless steel frame with a length of 50 m, and were treated at a constant length in an air atmosphere at a temperature of 230° C. for 3 hours to make them flame resistant. Then, in a nitrogen gas atmosphere, the temperature was raised from room temperature to 800°C for 50 minutes at 800°C.
The mixture was carbonized and emulsified for 20 minutes to produce the carbon fiber porous hollow fiber membrane of the present invention.

Each of these four types of hollow fiber membranes has an inner diameter of 380±10
The film thickness was 50±5 μm.

Table 1 shows the results of measuring single fiber strength and elongation, specific surface area, maximum pore radius, total pore volume, radius of curvature when bent, water permeation rate, and heat resistance of these hollow fiber membranes.

From Table 1, it can be seen that the maximum value of the pore radius becomes smaller as the amount of the (AN/MMA) block copolymer that is the compatibilizer (D) increases.

Furthermore, Figure 1 shows these four types of hollow fiber membranes (experimental corrosion 1 to 4).
) shows the pore volume differential curve.

Table 1 Example 2 AN 95 mol%, MA 4 mol%, itaconic acid (hereinafter referred to as I
Specific viscosity 0.21 composed of 1 mol% (abbreviated as A)
AN/MA/IA copolymer and Nagibutsu 87 mol%, MA
MMA/M with a specific viscosity of 0.19 composed of 13 mol%
A specific viscosity composed of a thermally decomposable polymer '(B) which is a copolymer and 30 mol% of AN prepared by the method below, 65 mol% of MMA, and 5 mol% of vinyl acetate (hereinafter abbreviated as VAc). Solvent (C) was mixed with compatibilizer (D2), which is a block polymer of 0°18, at the mixing ratio shown in Table 2.
The polymer was dissolved in dimethylacetamide (hereinafter abbreviated as DMAc) at a polymer concentration of 24% by weight.

Preparation of compatibilizer (D2) Dissolve 1 part of dichlorohexanone peroxide (Peroxa H1 manufactured by NOF Corporation) in 100 parts of MMA, and dissolve 800 parts of pure water.
and Pellex 0TP (manufactured by Nippon Oil & Fats Co., Ltd.) as an emulsifier.
After adding part to the reaction vessel and thoroughly replacing with inert gas,
0. After adjusting the pH to 3 with 76 parts of sulfuric acid and an aqueous sulfuric acid solution, polymerization was started. Stirring was continued to complete the first stage emulsion polymerization in 120 minutes.

Then, in the second stage, 60 parts of AN and VA were added to this emulsion.
After adding 10 parts of C, the temperature was raised to 70°C and stirring was continued again for 150 minutes.Furthermore, 4 parts of Glauber's salt was added and stirred for 30 minutes to complete polymerization. The polymer was taken out, filtered, washed with water, and dried to give a polymerization rate of 65%, a specific viscosity of 0.18, and a composition of AN.
A block polymer compatibilizer (D2) of 30 mol%/MMA 65 mol%/V'Ac 5 mol% was obtained.

Using the same nozzle as in Example 1, discharge in the same manner as in Example 1, and 5C! After running for n times, the fiber was introduced into a coagulation bath containing a 72% by weight DMAc aqueous solution at a temperature of 7°C, and was spun and coagulated. Then, it was washed in warm water at 60°C and stretched twice. Furthermore, it was stretched 6.2 times in hot water at 98°C. On the other hand, as a comparative sample (Experiment A69), five types of polymer blend hollow fibers were manufactured by processing under the same conditions except that the fibers were not stretched in hot water and passed through at a constant length, and then dried. By the same method as in Example 1, these five types of hollow fibers were set in a metal frame and flame resistant treated in an air atmosphere at a temperature of 240° C. for 3 hours.

Next, carbonization treatment was performed at a temperature of 900° C. for 10 minutes in a nitrogen atmosphere to produce a carbon fiber-based porous hollow fiber membrane. Table 2 shows various performances of the five types of hollow fiber membranes obtained.

Table 2 Hollow fiber basis weight Table 2 shows that as the blend amount of the thermally decomposable polymer increases, the total pore volume increases. The comparative sample Experiment/165 had closed pores and no communicating pores. The comparative sample, Experimental Layer 9, had poor flexibility and could not be used.

Figure 2 shows these five types of hollow fiber membranes (Experiments A5 to 9).
The pore volume cumulative distribution curve of FIG.

Example 3 Using the acrylic hollow fiber manufactured in Experimental Shop 7 of Example 2, it was heated at a speed of 20 m/Hr in an air atmosphere with a four-stage temperature distribution of 256/239/242/250'C. Flame resistant treated. Next, porous hollow fiber membranes of the present invention were manufactured by performing porous treatment at a rate of 15 m/Hr at the carbonization temperature in a nitrogen atmosphere shown in Table 3. Table 3 shows the various performances of these fibers.

Figure 6 also shows these four types of hollow fiber membranes (Experiment A 10
The pore volume cumulative distribution curves of ~16) are shown.

Table 6 From Table 3, it can be seen that as the carbonization temperature increases, the maximum value of the pore radius decreases and the total pore volume decreases, but the heat resistance increases.

Additional note 1, the acrylonitrile polymer (A) is polyacrylonitrile, acrylonitrile-methacrylic acid copolymer,
Acrylonitrile-methyl acrylate-itaconic acid copolymer or acrylonitrile-methyl acrylate-
4. The method according to item 3 or 4, wherein the copolymer is a methacrylic acid copolymer.

2. The thermally decomposable polymer (B) is a homopolymer of an aromatic vinyl monomer, an aliphatic vinyl monomer, or a methacrylate monomer, or a polymer containing 51 mol% or more of these monomer units and a polymer other than acrylonitrile. Other copolymerizable monomer units 49
5. The method according to item 3 or 4, wherein the copolymer is composed of mol % or less.

6. The method according to item 3 or 4, wherein the thermally decomposable polymer (B) is a styrene polymer, a vinyl chloride polymer, or a methyl methacrylate polymer.

4. The method according to item 3 or 4, wherein the acrylonitrile polymer (A) has a specific viscosity of 0°1 to 0.4.

5. The method according to item 6 or 4, wherein the acrylonitrile polymer (A) has a specific viscosity of 0°2 to 0.6.

6. The method according to item 3 or 4, wherein the thermally decomposable polymer (B) has a specific viscosity of 0.1 to 0.4.

Z. The method according to item 3 or 4, wherein the thermally decomposable polymer (B) has a specific viscosity of 0.2 to 0.3.

8. The compatibilizer (D) is compatible with the acrylonitrile polymer (segmented polymer that is compatible with Shu or composed of the same monomer) and the thermally decomposable polymer (B). or a graft copolymer or a block copolymer containing segment (b) composed of the same monomer in the same polymer chain.

9 The compatibilizer (D) is 60 mol% or more of acrylonitrile, 10 mol% or more of monomers that are constituent components of the thermally decomposable polymer (B), and 10 mol% or less of other monomers copolymerizable with these. The fourth item is characterized in that it is composed of
Manufacturing method described in section.

10. Acrylonitrile polymer (A1 10-90% by weight, thermally decomposable polymer (B) 10-90% by weight, and compatibilizer (D) 0-5% by weight [A) component, (B) component and CD) The method according to item 3 or 4, characterized in that the ingredients are mixed so that the total amount of the ingredients is 100% by weight.

11. Acrylonitrile polymer fA) 20 to 80% by weight, thermally decomposable polymer (B) 20 to 80% by weight, and compatibilizer (D) 0 to 5% by weight [provided that A) component, (Bl component and (D 4. The method according to item 3 or 4, characterized in that the ingredients are mixed so that the total amount of the components is 100% by weight.

12. The process according to item 6 or 4, wherein the solvent (C) is selected from dimethylformamide, dimethylacetamide and dimethyl sulfoxide.

13. The manufacturing method according to item 3 or 4, characterized in that spinning is performed by a dry-wet spinning method.

14. The manufacturing method according to item 6 or 4, characterized in that the film is stretched by a multi-stage stretching method at a total stretching ratio of 3 times or more.

15. The manufacturing method according to item 6 or 4, wherein the flame resistant treatment is performed by controlling the elongation in the flame resistant treatment to a range of 15% or less.

16. The manufacturing method according to item 3 or 4, characterized in that the carbonization treatment is carried out while controlling tension.

[Brief explanation of the drawing]

Figure 1 shows the pore volume differential curves of hollow fiber membranes obtained in experiments A1 to A4 of Example 1, and Figure 2 shows the pore volume differential curves of experiments A1 to A4 of Example 2.
Hollow fiber membrane pore volume cumulative integral right curve obtained in 9, No. 6
The figure shows the pore volume cumulative distribution curves of the hollow fiber membranes obtained in Experiments 10 to 13 of Example 6.

Claims (1)

[Claims] 1. The hollow fiber membrane has pores continuously connected from the inner wall surface to the outer wall surface, and the maximum value of the pore radius determined from the pore volume differential curve exists in the range of 10 to 1000 nm. , the total pore volume is 0.1~1cm^3/g, and the radius of curvature when bent is 10c.
1 of the hollow fiber membrane measured by TGA.
A carbon fiber porous hollow fiber membrane having excellent heat resistance and having a decomposition temperature of 0% by weight of at least about 300°C. 2. The hollow fiber membrane according to item 1, which has a tensile elongation of at least 0.8%. 3. Mixing an acrylonitrile polymer (A) containing 90 to 100 mol% of acrylonitrile units, a thermally decomposable polymer (B) that is thermally decomposed at a temperature of 600°C or lower to reduce its molecular weight, and a solvent (C). After that, the acrylonitrile-based hollow fibers obtained by spinning and drawing were subjected to flame-retardant treatment, and then
2. The method for producing a hollow fiber membrane according to item 1, wherein the hollow fiber membrane is made porous by carbonization treatment at a temperature of 0° C. or higher. 4. The method according to item 3, characterized in that a compatibilizer (D) is further mixed with the acrylonitrile polymer (A), the thermally decomposable polymer (B), and the solvent (C).